Identification of Dental Pulpal Inflammatory Mediators & Neuroregulators Using HPLC: This study consists of an invivo, non-invasive investigation into dental pulp cooling, followed by a histological, chromatographic and immunohistochemical investigation into pulpal neurotransmitters, neuroregulators and inflammatory regulators as they relate to lowering of pulp temperatures. The central hypothesis of this work is that neural response of the pulp can be decreased by lowering its temperature without adverse effects on the tissue, and that sensory nerve activity (pain) and the microcirculation of the pulp are closely related through the elaboration of neurovascular and inflammatory mediators and initiators. This hypothesis will be tested by carrying out the following specific aims: (1) To evaluate the performance of the cooling device in vivo by assessing its ability to lower pulpal temperature without causing adverse pulpal effects through its application in the subhuman primate Macaca fascicularis. (2) To evaluate the performance of the cooling device non-invasively in humans, measuring sensory nerve activity and microcirculation in the pulp continuously in response to pulp cooling to: (a) determine neural response to lowered temperatures with concurrent use of a constant current pulp tester; (b) determine microcirculatory response to lowered temperature with concurrent use of a laser Doppler flow cytometer (LDFC). (3) Develop methodology to identify the presence of and quantify neuroregulators and precursors of inflammation in response to lowered pulp temperatures. Institution of experiments to determine presence of neuroregulators was initiated. This second track involved use of immediately extracted third molars with no caries or restorations which were immediately immersed in liquid nitrogen, split and the pulp tissue harvested. The pooled pulp tissue was prepared, known quantities of bradykinin and substance P added to the resultant, and processed using RP-HPLC to determine their recovery. The data was compared to standards previously established for both substances. Bradykinin recovered and detected using a MV detection system, but not substance P. RP-HPLC appears capable of detecting neurochemicals contained in dental pulp tissue, with further optimization necessary for tissue sample preparation and processing. Optimization includes the use of an electro-chemical detector and mass spectrometry (MS). The use of MS for peptide measurement should convey primary structural information in order that the peptide we think we are identifying is actually the one that is being identified. Recent work demonstrated that MS may be the method of choice in the identification of endogenous peptides and may be used to calibrate other analytical methods.